math help

What is 78/10 + 4/7?

What is 78/10 + 4/7?

Let's add

78
10
+
4
7

Step 1

Can you add yet? Nope! The denominators don't match. We need a common denominator. So next we take both denominators and multiply them. Next, take each numerator and multiply it by the denominator of the other term.

So, we multiply 78 by 7, and get 546, then we multiply 10 by 7 and get 70.

78/10 times 7

Now for the second term. You multiply 4 by 10, and get 40, then multiply 10 by 7 and get 70.

4/7 times 10

We now have a new problem, that looks like this:

546
70
+
40
70

Step 2

Since our denominators match, we can add the numerators.

546 + 40 = 586

Answer:

586
70

Step 3

Now, do we need to simplify this fraction?

First, we attempt to divide it by 2...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

586
70
÷ 2 =
293
35

Let's try dividing by that again...

Nope! So now we try the next greatest prime number, 3...

Nope! So now we try the next greatest prime number, 5...

Nope! So now we try the next greatest prime number, 7...

Nope! So now we try the next greatest prime number, 11...

Nope! So now we try the next greatest prime number, 13...

Nope! So now we try the next greatest prime number, 17...

Nope! So now we try the next greatest prime number, 19...

Nope! So now we try the next greatest prime number, 23...

Nope! So now we try the next greatest prime number, 29...

Nope! So now we try the next greatest prime number, 31...

Nope! So now we try the next greatest prime number, 37...

No good. 37 is larger than 35. So we're done reducing.

There you have it! Here's the final answer to 78/10 + 4/7

78
10
+
4
7
=
293
35
© 2014 Randy Tayler